Advances in Materials
Volume 9, Issue 1, March 2020, Pages: 1-7
Received: Nov. 22, 2019;
Accepted: Dec. 17, 2019;
Published: Mar. 23, 2020
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Aniedi Nyong, Materials Chemistry Research Unit, Department of Chemistry, Faculty of Physical Sciences, Akwa Ibom State University, Akwa Ibom State, Nigeria
Edet Nsi, Materials Chemistry Research Unit, Department of Chemistry, Faculty of Physical Sciences, Akwa Ibom State University, Akwa Ibom State, Nigeria
Joachim Awaka-Ama, Materials Chemistry Research Unit, Department of Chemistry, Faculty of Physical Sciences, Akwa Ibom State University, Akwa Ibom State, Nigeria
Godwin Udo, Materials Chemistry Research Unit, Department of Chemistry, Faculty of Physical Sciences, Akwa Ibom State University, Akwa Ibom State, Nigeria
The photodegradation of stearic acid has been studied through evaluation of changes in the contact angles of water and from absorbance measurements. The photodegradation of 0.02 M stearic acid coatings and solutions were initiated by TiO2 nanoparticles of average size of 9.80 ± 2.92 nm embedded in cements in 1.66 wt.%, 3.33 wt.%, 5.0 wt.% and 6.67 wt.% to generate modified cement composites with photocatalytic capability. It was noted that the photodegradation efficiencies increased with the increase in the weight-percent of TiO2 present in the modified cement samples. A modified Cassie-Baxter and the Langmuir-Hinselwood models were used to compute the rate constants, based on changes in the contact angles of water and in the concentration of the stearic acid respectively, on exposure to the UV light source. The modified Cassie-Baxter model successfully provided a route to relate the changes in water contact angle to the rate of photodegradation of a hydrophobic, long-chain stearic acid. The values of the rate constant estimated from both models increased with increase in the amount of TiO2 present in the modified cement samples. However, the rate constant values obtained from the modified Cassie-Baxter model were lower than those obtained from the Langmuir-Hinselwood model. The values of these rate contants were in the range of 0.11-0.50 hr-1 and 0.78-1.33 hr-1 as btained from the modified Cassie-Baxter and Langmuir-Hinselwood models respectively. This disparity in the values was attributed to a higher mobility of the charge carriers and free-radicals that induced the photodegradation in liquid medium as compared to the solid medium.
Comparative Evaluation of the Photodegradation of Stearic Acid by TiO2 - Modified Cement Under UV Irradiation Through Water Contact Angle and Absorbance Studies, Advances in Materials.
Vol. 9, No. 1,
2020, pp. 1-7.
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